Installation; Use With Intelligent Telephone Modems - Campbell SC932C User Manual

SC932C 9-Pin to RS232-DCE Interface
The SC932C is used to interface a Campbell Scientific datalogger to modem devices that are
configured with an RS232 DCE (Data Communications Equipment) serial port. The most
common application is to allow the connection of a RAD-SRM short haul modem or third
party telephone modem to a datalogger.
The SC932C has the following features:
• Generates true RS232 signal levels to the DCE device, resulting in good noise immunity.
• Powered from the 5V supply of the datalogger, which is also available to provide power to
the DCE, if required for line-powered modems.
• Generates the required ring signal to wake up the datalogger, either when characters are
received or when there is a ring signal from the DCE.
• Allows simultaneous connection of synchronous devices (e.g. Storage Modules) to the
datalogger.
• Provides a mechanism for the datalogger to control the line state of intelligent modems
via DTR handshaking control.
• Convenient 'jumperless' design.

1. Installation

2. Use with Intelligent Telephone Modems

Use the SC12 ribbon cable (provided) to connect the datalogger's 9-pin serial port
to the 9-pin connector on the SC932C. The SC932C can usually be connected to
the RS232 device by plugging the SC932C directly into the serial connector on the
RS232 device. No further configuration is normally required.
A typical application with a RAD modem would comprise:
Figure 1 SC932C Connected to RAD-SRM Short-Haul Modem
If the RS232 device does not have a suitable 25-way 'D' socket, you may need an
adaptor cable (see Appendix A).
If an 'intelligent' telephone modem is being used, configure it to allow the
SC932C to control its line status via the DTR line. This can prevent the modem
staying on-line unnecessarily, which can lead to excessive telephone charges and
also delay reconnection to the datalogger.
SC932C
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